Planetary transmissions having a stationary member and an input member

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least eight forward speed ratios and one reverse speed ratio. The transmission family members include three planetary gear sets having seven torque-transmitting mechanisms and a grounded planetary gear member. The powertrain includes an engine and torque converter that is continuously connected to at least one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The seven torque-transmitting mechanisms provide interconnections between various gear members and the transmission housing, and are operated in combinations of four to establish at least eight forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a family of power transmissions havingthree planetary gear sets that are controlled by seventorque-transmitting devices to provide at least eight forward speedratios and at least one reverse speed ratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times. The number of forward speed ratios that are availablein the transmission determines the number of times the engine torquerange is repeated. Early automatic transmissions had two speed ranges.This severely limited the overall speed range of the vehicle andtherefore required a relatively large engine that could produce a widespeed and torque range. This resulted in the engine operating at aspecific fuel consumption point during cruising, other than the mostefficient point. Therefore, manually-shifted (countershafttransmissions) were the most popular.

With the advent of three- and four-speed automatic transmissions, theautomatic shifting (planetary gear) transmission increased in popularitywith the motoring public. These transmissions improved the operatingperformance and fuel economy of the vehicle. The increased number ofspeed ratios reduces the step size between ratios and therefore improvesthe shift quality of the transmission by making the ratio interchangessubstantially imperceptible to the operator under normal vehicleacceleration.

It has been suggested that the number of forward speed ratios beincreased to six or more. Six-speed transmissions are disclosed in U.S.Pat. No. 4,070,927 issued to Polak on Jan. 31, 1978; and U.S. Pat. No.6,422,969 issued to Raghavan and Usoro on Jul. 23, 2002.

Six-speed transmissions offer several advantages over four- andfive-speed transmissions, including improved vehicle acceleration andimproved fuel economy. While many trucks employ power transmissionshaving six or more forward speed ratios, passenger cars are stillmanufactured with three- and four-speed automatic transmissions andrelatively few five or six-speed devices due to the size and complexityof these transmissions.

Seven-speed transmissions are disclosed in U.S. Pat. No. 6,623,397issued to Raghavan, Bucknor and Usoro. Eight speed transmissions aredisclosed in U.S. Pat. No. 6,425,841 issued to Haka. The Hakatransmission utilizes three planetary gear sets and six torquetransmitting devices, including two brakes and two clutches, to provideeight forward speed ratios and a reverse speed ratio. One of theplanetary gear sets is positioned and operated to establish two fixedspeed input members for the remaining two planetary gear sets. Seven-,eight- and nine-speed transmissions provide further improvements inacceleration and fuel economy over six-speed transmissions. However,like the six-speed transmissions discussed above, the development ofseven-, eight- and nine-speed transmissions has been precluded becauseof complexity, size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved familyof transmissions having three planetary gear sets controlled to provideat least eight forward speed ratios and at least one reverse speedratio.

In one aspect of the present invention, the family of transmissions hasthree planetary gear sets, each of which includes a first, second andthird member, which members may comprise a sun gear, a ring gear, or aplanet carrier assembly member.

In referring to the first, second and third gear sets in thisdescription and in the claims, these sets may be counted “first” to“third” in any order in the drawings (i.e., left to right, right toleft, etc.).

In another aspect of the present invention, each of the planetary gearsets may be of the single pinion-type or of the double pinion-type.

In yet another aspect of the present invention, a first member of thesecond planetary gear set is continuously connected with a stationarymember (transmission housing).

In yet a further aspect of the invention, each family memberincorporates an input shaft which is continuously connected with amember of the planetary gear sets, and an output shaft which iscontinuously connected with another member of the planetary gear sets.

In still a further aspect of the invention, a first torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst planetary gear set with a member of the third planetary gear set.

In another aspect of the invention, a second torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thesecond planetary gear set with a member of the first or third planetarygear set.

In a still further aspect of the invention, a third torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thethird planetary gear set with a member of the first or second planetarygear set.

In a still further aspect of the invention, a fourth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst planetary gear set with a member of the second or third planetarygear set.

In a still further aspect of the invention, a fifth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst or third planetary gear set with another member of the first,second or third planetary gear set.

In still another aspect of the invention, a sixth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear sets. Alternatively, the sixthtorque-transmitting mechanism, such as a brake, selectively connects amember of the first, second or third planetary gear set with thestationary member (transmission case).

In still another aspect of the invention, a seventh torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst or third planetary gear set with another member of the first,second or third planetary gear set. Alternatively, the seventhtorque-transmitting mechanism, such as a brake, selectively connects amember of the first or third planetary gear set with the stationarymember (transmission case).

In still another aspect of the invention, the seven torque-transmittingmechanisms are selectively engageable in combinations of four to yieldat least eight forward speed ratios and at least one reverse speedratio.

The above objects and other objects, features, and advantages of thepresent invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

FIG. 1 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1 a;

FIG. 2 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 2 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2 a;

FIG. 3 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 3 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3 a;

FIG. 4 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 4 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4 a;

FIG. 5 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 5 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5 a;

FIG. 6 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 6 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6 a;

FIG. 7 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 7 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7 a;

FIG. 8 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 8 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8 a;

FIG. 9 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 9 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9 a;

FIG. 10 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 10 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 10 a;

FIG. 11 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 11 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 11 a;

FIG. 12 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 12 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 12 a;

FIG. 13 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

FIG. 13 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 13 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like characters represent the same orcorresponding parts throughout the several views, there is shown in FIG.1 a a powertrain 10 having a conventional engine and torque converter12, a planetary transmission 14, and a conventional final drivemechanism 16.

The planetary transmission 14 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 18, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 18 includesthree planetary gear sets 20, 30 and 40.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly 26. The planet carrier assembly26 includes a plurality of pinion gears 27 rotatably mounted on acarrier member 29 and disposed in meshing relationship with both the sungear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the sun gear member 32 and the ring gear member 34.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47 rotatablymounted on a carrier member 49 and disposed in meshing relationship withboth the sun gear member 42 and the ring gear member 44.

The planetary gear arrangement also includes seven torque-transmittingmechanisms 50, 52, 54, 56, 57, 58 and 59. The torque-transmittingmechanisms 50, 52, 54, 56 and 57 are rotating-type torque-transmittingmechanisms, commonly termed clutches. The torque-transmitting mechanisms58 and 59 are stationary-type torque transmitting mechanisms, commonlytermed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member22. The output shaft 19 is continuously connected with the ring gearmember 44. The sun gear member 32 is continuously connected with thetransmission housing 60.

The sun gear member 22 is selectively connectable with the planetcarrier assembly member 46 through the clutch 50. The ring gear member24 is selectively connectable with the planet carrier assembly member 36through the clutch 52. The planet carrier assembly member 26 isselectively connectable with the planet carrier assembly member 46through the clutch 54. The planet carrier assembly member 26 isselectively connectable with the sun gear member 42 through the clutch56. The ring gear member 34 is selectively connectable with the sun gearmember 42 through the clutch 57. The ring gear member 34 is selectivelyconnectable with the transmission housing 60 through the brake 58. Theplanet carrier assembly member 46 is selectively connectable with thetransmission housing 60 through the brake 59.

As shown in FIG. 1 b, and in particular the truth table disclosedtherein, the torque-transmitting mechanisms are selectively engaged incombinations of four to provide eight forward speed ratios (including anextra first speed ratio: 1′) and two reverse speed ratios.

The extra reverse speed ratio (R′) is established with the engagement ofthe clutches 52, 56 and the brakes 58, 59. The clutch 52 connects thering gear member 24 with the planet carrier assembly member 36. Theclutch 56 connects the planet carrier assembly member 26 with the sungear member 42. The brake 58 connects the ring gear member 34 with thetransmission housing 60. The brake 59 connects the planet carrierassembly member 46 with the transmission housing 60. The sun gear member22 rotates at the same speed as the input shaft 17. The planet carrierassembly member 26 rotates at the same speed as the sun gear member 42.The ring gear member 24 and planetary gear set 30 do not rotate. Thespeed of the planet carrier assembly member 26 is determined from thespeed of the sun gear member 22 and the ring gear/sun gear tooth ratioof the planetary gear set 20. The planet carrier assembly member 46 doesnot rotate. The ring gear member 44 rotates at the same speed as theoutput shaft 19. The ring gear member 44, and therefore the output shaft19, rotates at a speed determined from the speed of the sun gear member42 and the ring gear/sun gear tooth ratio of the planetary gear set 40.The numerical value of the extra reverse speed ratio (R′) is determineutilizing the ring gear/sun gear tooth ratios of the planetary gear sets20 and 40.

The reverse speed ratio is established with the engagement of theclutches 52, 56, 57 and the brake 59. The clutch 52 connects the ringgear member 24 with the planet carrier assembly member 36. The clutch 56connects the planet carrier assembly member 26 with the sun gear member42. The clutch 57 connects the ring gear member 34 with the sun gearmember 42. The brake 59 connects the planet carrier assembly member 46with the transmission housing 60. The sun gear member 22 rotates at thesame speed as the input shaft 17. The planet carrier assembly member 26rotates at the same speed as the sun gear member 42 and the ring gearmember 34. The ring gear member 24 rotates at the same speed as theplanet carrier assembly member 36. The speed of the planet carrierassembly member 26 is determined from the speed of the ring gear member24, the speed of the sun gear member 22, and the ring gear/sun geartooth ratio of the planetary gear set 20. The sun gear member 32 doesnot rotate. The planet carrier assembly member 36 rotates at a speeddetermined from the speed of the ring gear member 34 and the ringgear/sun gear tooth ratio of the planetary gear set 30. The planetcarrier assembly member 46 does not rotate. The ring gear member 44rotates at the same speed as the output shaft 19. The speed of the ringgear member 44, and therefore the output shaft 19, is determined fromthe speed of the sun gear member 42 and the ring gear/sun gear toothratio of the planetary gear set 40. The numerical value of the reversespeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 20, 30 and 40.

The first forward speed ratio is established with the engagement of theclutches 52, 54, 57 and the brake 59. The clutch 52 connects the ringgear member 24 with the planet carrier assembly member 36. The clutch 54connects the planet carrier assembly member 26 with the planet carrierassembly member 46. The clutch 57 connects the ring gear member 34 withthe sun gear member 42. The brake 59 connects the planet carrierassembly member 46 with the transmission housing 60. The sun gear member22 rotates at the same speed as the input shaft 17. The planet carrierassembly member 26, sun gear member 32 and planet carrier assemblymember 46 do not rotate. The ring gear member 24 rotates at the samespeed as the planet carrier assembly member 36. The speed of the ringgear member 24 is determined from the speed of the sun gear member 22and the ring gear/sun gear tooth ratio of the planetary gear set 20. Thering gear member 34 rotates at the same speed as the sun gear member 42.The speed of the ring gear member 34 is determined from the speed of theplanet carrier assembly member 36 and the ring gear/sun gear tooth ratioof the planetary gear set 30. The ring gear member 44 rotates at thesame speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the sun gear member 42 and the ring gear/sun gear tooth ratioof the planetary gear set 40. The numerical value of the first forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 20, 30 and 40.

The extra first forward speed ratio (1′) is established with theengagement of the clutches 52, 54, 56 and the brake 58. The clutch 52connects the ring gear member 24 with the planet carrier assembly member36. The clutch 54 connects the planet carrier assembly member 26 withthe planet carrier assembly member 46. The clutch 56 connects the planetcarrier assembly member 26 with the sun gear member 42. The brake 58connects the ring gear member 34 with the transmission housing 60. Thesun gear member 22 rotates at the same speed as the input shaft 17. Theplanet carrier assembly member 26 rotates at the same speed as theplanetary gear set 40 and the output shaft 19. The ring gear member 24and planetary gear set 30 do not rotate. The speed of the planet carrierassembly member 26, and therefore the output shaft 19, is determinedfrom the speed of the sun gear member 22 and the ring gear/sun geartooth ratio of the planetary gear set 20. The numerical value of theextra first forward speed ratio (1′) is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 20.

The second forward speed ratio is established with the engagement of theclutches 52, 54, 57 and the brake 58. The clutch 52 connects the ringgear member 24 with the planet carrier assembly member 36. The clutch 54connects the planet carrier assembly member 26 with the planet carrierassembly member 46. The clutch 57 connects the ring gear member 34 withthe sun gear member 42. The brake 58 connects the ring gear member 34with the transmission housing 60. The sun gear member 22 rotates at thesame speed as the input shaft 17. The planet carrier assembly member 26rotates at the same speed as the planet carrier assembly member 46. Thering gear member 24, planetary gear set 30 and sun gear member 42 do notrotate. The speed of the planet carrier assembly member 26 is determinedfrom the speed of the sun gear member 22 and the ring gear/sun geartooth ratio of the planetary gear set 20. The ring gear member 44rotates at the same speed as the output shaft 19. The speed of the ringgear member 44, and therefore the output shaft 19, is determined fromthe speed of the planet carrier assembly member 46 and the ring gear/sungear tooth ratio of the planetary gear set 40. The numerical value ofthe second forward speed ratio is determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 20 and 40.

The third forward speed ratio is established with the engagement of theclutches 52, 54, 56 and 57. The clutch 52 connects the ring gear member24 with the planet carrier assembly member 36. The clutch 54 connectsthe planet carrier assembly member 26 with the planet carrier assemblymember 46. The clutch 56 connects the planet carrier assembly member 26with the sun gear member 42. The clutch 57 connects the ring gear member34 with the sun gear member 42. The sun gear member 22 rotates at thesame speed as the input shaft 17. The planet carrier assembly member 26rotates at the same speed as the ring gear member 34, the planetary gearset 40, and the output shaft 19. The ring gear member 24 rotates at thesame speed as the planet carrier assembly member 36. The planet carrierassembly member 26, and therefore the output shaft 19, rotates at aspeed determined from the speed of the ring gear member 24, the speed ofthe sun gear member 22, and the ring gear/sun gear tooth ratio of theplanetary gear set 20. The sun gear member 32 does not rotate. The speedof the planet carrier assembly member 36 is determined from the speed ofthe ring gear member 34 and the ring gear/sun gear tooth ratio of theplanetary gear set 30. The numerical value of the third forward speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20 and 30.

The fourth forward speed ratio is established with the engagement of theclutches 50, 52, 54 and 57. The clutch 50 connects the sun gear member22 with the planet carrier assembly member 46. The clutch 52 connectsthe ring gear member 24 with the planet carrier assembly member 36. Theclutch 54 connects the planet carrier assembly member 26 with the planetcarrier assembly member 46. The clutch 57 connects the ring gear member34 with the sun gear member 42. The planetary gear set 20, planetcarrier assembly member 36 and planet carrier assembly member 46 rotateat the same speed as the input shaft 17. The sun gear member 32 does notrotate. The ring gear member 34 rotates at the same speed as the sungear member 42. The speed of the ring gear member 34 is determined fromthe speed of the planet carrier assembly member 36 and the ring gear/sungear tooth ratio of the planetary gear set 30. The ring gear member 44rotates at the same speed as the output shaft 19. The speed of the ringgear member 44, and therefore the output shaft 19, is determined fromthe speed of the planet carrier assembly member 46, the speed of the sungear member 42, and the ring gear/sun gear tooth ratio of the planetarygear set 40. The numerical value of the fourth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 30 and 40.

The fifth forward speed ratio is established with the engagement of theclutches 50, 52, 54 and 56. In this configuration, the input shaft 17 isdirectly connected to the output shaft 19. The numerical value of thefifth forward speed ratio is 1.

The sixth forward speed ratio is established with the engagement of theclutches 50, 52, 56 and 57. The clutch 50 connects the sun gear member22 with the planet carrier assembly member 46. The clutch 52 connectsthe ring gear member 24 with the planet carrier assembly member 36. Theclutch 56 connects the planet carrier assembly member 26 with the sungear member 42. The clutch 57 connects the ring gear member 34 with thesun gear member 42. The sun gear member 22 and planet carrier assemblymember 46 rotate at the same speed as the input shaft 17. The planetcarrier assembly member 26 rotates at the same speed as the sun gearmember 42 and the ring gear member 34. The ring gear member 24 rotatesat the same speed as the planet carrier assembly member 36. The speed ofthe planet carrier assembly member 26 is determined from the speed ofthe ring gear member 24, the speed of the sun gear member 22, and thering gear/sun gear tooth ratio of the planetary gear set 20. The sungear member 32 does not rotate. The speed of the planet carrier assemblymember 36 is determined from the speed of the ring gear member 34 andthe ring gear/sun gear tooth ratio of the planetary gear set 30. Thering gear member 44 rotates at the same speed as the output shaft 19.The ring gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member46, the speed of the sun gear member 42, and the ring gear/sun geartooth ratio of the planetary gear set 40. The numerical value of thesixth forward speed ratio is determined utilizing the ring gear/sun geartooth ratios of the planetary gear sets 20, 30 and 40.

The seventh forward speed ratio is established with the engagement ofthe clutches 50, 52, 56 and the brake 58. The clutch 50 connects the sungear member 22 with the planet carrier assembly member 46. The clutch 52connects the ring gear member 24 with the planet carrier assembly member36. The clutch 56 connects the planet carrier assembly member 26 withthe sun gear member 42. The brake 58 connects the ring gear member 34with the transmission housing 60. The sun gear member 22 and planetcarrier assembly member 46 rotate at the same speed as the input shaft17. The planet carrier assembly member 26 rotates at the same speed asthe sun gear member 42. The ring gear member 24 and planetary gear set30 do not rotate. The speed of the planet carrier assembly member 26 isdetermined from the speed of the sun gear member 22 and the ringgear/sun gear tooth ratio of the planetary gear set 20. The ring gearmember 44 rotates at the same speed as the output shaft 19. The ringgear member 44, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the planet carrier assembly member 46, thespeed of the sun gear member 42 and the ring gear/sun gear tooth ratioof the planetary gear set 40. The numerical value of the seventh forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratiosof the planetary gear sets 20 and 40.

The eighth forward speed ratio is established with the engagement of theclutches 50, 56, 57 and the brake 58. The clutch 50 connects the sungear member 22 with the planet carrier assembly member 46. The clutch 56connects the planet carrier assembly member 26 with the sun gear member42. The clutch 57 connects the ring gear member 24 with the sun gearmember 42. The brake 58 connects the ring gear member 34 with thetransmission housing 60. The sun gear member 22 and planet carrierassembly member 46 rotate at the same speed as the input shaft 17. Theplanet carrier assembly member 26, planetary gear set 30, and sun gearmember 42 do not rotate. The ring gear member 44 rotates at the samespeed as the output shaft 19. The ring gear member 44, and therefore theoutput shaft 19, rotates at a speed determined from the speed of theplanet carrier assembly member 46 and the ring gear/sun gear tooth ratioof the planetary gear set 40. The numerical value of the eighth forwardspeed ratio is determined utilizing the ring gear/sun gear tooth ratioof the planetary gear set 40.

As set forth above, the engagement schedule for the torque-transmittingmechanisms is shown in the truth table of FIG. 1 b. This truth tablealso provides an example of speed ratios that are available utilizingthe ring gear/sun gear tooth ratios given by way of example in FIG. 1 b.The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 20;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set 30;and the N_(R3)/N_(S3) value is the tooth ratio of the planetary gear set40. Also, the chart of FIG. 1 b describes the ratio steps that areattained utilizing the sample of tooth ratios given. For example, thestep ratio between the first and second forward speed ratios is 1.96,while the step ratio between the reverse and first forward ratio is−1.00.

FIG. 2 a shows a powertrain 110 having a conventional engine and torqueconverter 12, a planetary transmission 114, and a conventional finaldrive mechanism 16.

The planetary transmission 114 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 118, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 118 includesthree planetary gear sets 120, 130 and 140.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly 126. The planet carrierassembly 126 includes a plurality of pinion gears 127 rotatably mountedon a carrier member 129 and disposed in meshing relationship with boththe sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of pinion gears 137 rotatablymounted on a carrier member 139 and disposed in meshing relationshipwith both the sun gear member 132 and the ring gear member 134.

The planetary gear set 140 includes a sun gear member 142, a ring gearmember 144, and a planet carrier assembly member 146. The planet carrierassembly member 146 includes a plurality of pinion gears 147 rotatablymounted on a carrier member 149 and disposed in meshing relationshipwith both the sun gear member 142 and the ring gear member 144.

The planetary gear arrangement 118 also includes seventorque-transmitting mechanisms 150, 152, 154, 156, 157, 158 and 159. Thetorque-transmitting mechanisms 150, 152, 154, 156, 157 and 158 arerotating-type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 159 is a stationary-type torquetransmitting mechanism, commonly termed brake or reaction clutch.

The input shaft 17 is continuously connected with the sun gear member122. The output shaft 19 is continuously connected with the ring gearmember 144. The sun gear member 132 is continuously connected with thetransmission housing 160.

The ring gear member 124 is selectively connectable with the ring gearmember 134 through the clutch 150. The ring gear member 124 isselectively connectable with the planet carrier assembly member 136through the clutch 152. The planet carrier assembly member 126 isselectively connectable with the planet carrier assembly member 146through the clutch 154. The ring gear member 134 is selectivelyconnectable with the sun gear member 142 through the clutch 156. Theplanet carrier assembly member 136 is selectively connectable with thesun gear member 142 through the clutch 157. The planet carrier assemblymember 126 is selectively connectable with the sun gear member 122through the clutch 158. The planet carrier assembly member 146 isselectively connectable with the transmission housing 160 through thebrake 159.

The truth table of FIG. 2 b describes the engagement sequence utilizedto provide eight forward speed ratios and three reverse speed ratios inthe planetary gear arrangement 118 shown in FIG. 2 a.

The truth tables given in FIGS. 2 b, 3 b, 4 b, 5 b, 6 b, 7 b, 8 b, 9 b,10 b, 11 b, 12 b and 13 b show the engagement sequences for thetorque-transmitting mechanisms to provide at least eight forward speedratios and at least one reverse ratio. As shown and described above forthe configuration in FIG. 1 a, those skilled in the art will understandfrom the respective truth tables how the speed ratios are establishedthrough the planetary gear sets identified in the written description.

As set forth above, the truth table of FIG. 2 b describes the engagementsequence of the torque-transmitting mechanisms utilized to provide threereverse drive ratios and eight forward speed ratios. The truth tablealso provides an example of the ratios that can be attained with thefamily members shown in FIG. 2 a utilizing the sample tooth ratios givenin FIG. 2 b. The. N_(R1)/N_(S1) value is the tooth ratio of theplanetary gear set 120; the N_(R2)/N_(S2) value is the tooth ratio ofthe planetary gear set 130; and the N_(R3)/N_(S3) value is the toothratio of the planetary gear set 140. Also shown in FIG. 2 b are theratio steps between single step ratios in the forward direction as wellas the reverse to first ratio step ratio. For example, the first tosecond step ratio is 1.46.

Turning to FIG. 3 a, a powertrain 210 includes the engine and torqueconverter 12, a planetary transmission 214, and a final drive mechanism16. The planetary transmission 214 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 218, and an output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 218 includes three planetary gear sets 220, 230 and 240.

The planetary gear set 220 includes a sun gear member 222, a ring gearmember 224, and a planet carrier assembly 226. The planet carrierassembly 226 includes a plurality of pinion gears 227 rotatably mountedon a carrier member 229 and disposed in meshing relationship with boththe sun gear member 222 and the ring gear member 224.

The planetary gear set 230 includes a sun gear member 232, a ring gearmember 234, and a planet carrier assembly member 236. The planet carrierassembly member 236 includes a plurality of pinion gears 237 rotatablymounted on a carrier member 239 and disposed in meshing relationshipwith both the sun gear member 232 and the ring gear member 234.

The planetary gear set 240 includes a sun gear member 242, a ring gearmember 244, and a planet carrier assembly member 246. The planet carrierassembly member 246 includes a plurality of pinion gears 247 rotatablymounted on a carrier member 249 and disposed in meshing relationshipwith both the sun gear member 242 and the ring gear member 244.

The planetary gear arrangement 218 also includes seventorque-transmitting mechanisms 250, 252, 254, 256, 257, 258 and 259. Thetorque-transmitting mechanisms 250, 252, 254, 256 257 and 258 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 259 is a stationary-type torquetransmitting mechanism, commonly termed brake or reaction clutch.

The input shaft 17 is continuously connected with the sun gear member222. The output shaft 19 is continuously connected with the ring gearmember 244. The sun gear member 232 is continuously connected with thetransmission housing 260.

The planet carrier assembly member 226 is selectively connectable withthe ring gear member 234 through the clutch 250. The planet carrierassembly member 226 is selectively connectable with the planet carrierassembly member 246 through the clutch 252. The ring gear member 224 isselectively connectable with the planet carrier assembly member 236through the clutch 254. The ring gear member 234 is selectivelyconnectable with the sun gear member 242 through the clutch 256. Theplanet carrier assembly member 236 is selectively connectable with thesun gear member 242 through the clutch 257. The ring gear member 224 isselectively connectable with the sun gear member 222 through the clutch258. The planet carrier assembly member 246 is selectively connectablewith the transmission housing 260 through the brake 259.

As shown in the truth table in FIG. 3 b, the torque-transmittingmechanisms are engaged in combinations of four to establish eightforward speed ratios, five reverse speed ratios, and an extra fourthforward speed ratio.

As previously set forth, the truth table of FIG. 3 b describes thecombinations of engagements utilized for the forward and reverse speedratios. The truth table also provides an example of speed ratios thatare available with the family member described above. These examples ofspeed ratios are determined utilizing the tooth ratios given in FIG. 3b. The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set220; the N_(R2)/N_(S2) value is the tooth ratio of the planetary gearset 230; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 240. Also depicted in FIG. 3 b is a chart representing theratio steps between adjacent forward speed ratios and between the firstand reverse speed ratio. For example, the first to second ratiointerchange has a step of 1.46.

A powertrain 310, shown in FIG. 4 a, includes the engine and torqueconverter 12, a planetary transmission 314, and the final drivemechanism 16. The planetary transmission 314 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 318, and output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 318 includes three planetary gear sets 320, 330 and 340.

The planetary gear set 320 includes a sun gear member 322, a ring gearmember 324, and a planet carrier assembly member 326. The planet carrierassembly member 326 includes a plurality of pinion gears 327 rotatablymounted on a carrier member 329 and disposed in meshing relationshipwith both the sun gear member 322 and the ring gear member 324.

The planetary gear set 330 includes a sun gear member 332, a ring gearmember 334, and a planet carrier assembly member 336. The planet carrierassembly member 336 includes a plurality of pinion gears 337 rotatablymounted on a carrier member 339 and disposed in meshing relationshipwith both the sun gear member 332 and the ring gear member 334.

The planetary gear set 340 includes. a sun gear member 342, a ring gearmember 344, and a planet carrier assembly member 346. The planet carrierassembly member 346 includes a plurality of pinion gears 347 rotatablymounted on a carrier member 349 and disposed in meshing relationshipwith both the sun gear member 342 and the ring gear member 344.

The planetary gear arrangement 318 also includes seventorque-transmitting mechanisms 350, 352, 354, 356, 357; 358 and 359. Thetorque-transmitting mechanisms 350, 352, 354, 356, 357, 358 and 359 areall rotating type torque-transmitting mechanisms, commonly termedclutches.

The input shaft 17 is continuously connected with the sun gear member322. The output shaft 19 is continuously connected with the ring gearmember 344. The sun gear member 332 is continuously connected with thetransmission housing 360.

The ring gear member 324 is selectively connectable with the planetcarrier assembly member 346 through the clutch 350. The planet carrierassembly member 326 is selectively connectable with the sun gear member342 through the clutch 352. The planet carrier assembly member .326 isselectively connectable with the planet carrier assembly member 346through the clutch 354. The ring gear member 334 is selectivelyconnectable with the sun gear member 342 through the clutch 356. Thering gear member 334 is selectively connectable with the planet carrierassembly member 346 through the clutch 357. The ring gear member 324 isselectively connectable with the sun gear member 322 through the clutch358. The ring gear member 334 is selectively connectable with the planetcarrier assembly member 336 through the clutch 359.

The truth table shown in FIG. 4 b describes the engagement combinationand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios. A sample of the numerical valuesfor the ratios is also provided in the truth table of FIG. 4 b. Thesevalues are determined utilizing the ring gear/sun gear tooth ratios alsogiven in FIG. 4 b. The N_(R1)/N_(S1) value is the tooth ratio for theplanetary gear set 320; the N_(R2)/N_(S2) value is the tooth ratio forthe planetary gear set 330; and the N_(R3)/N_(S3) value is the toothratio for the planetary gear set 340. Also given in FIG. 4 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe reverse to first forward speed ratio. For example, the first tosecond forward speed ratio step is 1.43.

A powertrain 410, shown in FIG. 5 a, includes the engine and torqueconverter 12, a planetary transmission 414 and the final drive mechanism16. The planetary transmission 414 includes a planetary gear arrangement418, input shaft 17 and output shaft 19. The planetary gear arrangement418 includes three simple planetary gear sets 420, 430 and 440.

The planetary gear set 420 includes a sun gear member 422, a ring gearmember 424, and a planet carrier assembly 426. The planet carrierassembly 426 includes a plurality of pinion gears 427 rotatably mountedon a carrier member 429 and disposed in meshing relationship with boththe sun gear member 422 and the ring gear member 424.

The planetary gear set 430 includes a sun gear member 432, a ring gearmember 434, and a planet carrier assembly member 436. The planet carrierassembly member 436 includes a plurality of pinion gears 437 rotatablymounted on a carrier member 439 and disposed in meshing relationshipwith both the ring gear member 434 and the sun gear member 432.

The planetary gear set 440 includes a sun gear member 442, a ring gearmember 444, and a planet carrier assembly member 446. The planet carrierassembly member 446 includes a plurality of pinion gears 447 rotatablymounted on a carrier member 449 and disposed in meshing relationshipwith both the sun gear member 442 and the ring gear member 444.

The planetary gear arrangement 418 also includes seventorque-transmitting mechanisms 450, 452, 454, 456, 457, 458 and 459. Thetorque-transmitting mechanisms 450, 452, 454, 456 and 457 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 458 and 459 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member422. The output shaft 19 is continuously connected with the ring gearmember 444. The sun gear member 432 is continuously connected with thetransmission housing 460.

The sun gear member 422 is selectively connectable with the planetcarrier assembly member 436 through the clutch 450. The ring gear member424 is selectively connectable with the planet carrier assembly member436 through the clutch 452. The ring gear member 424 is selectivelyconnectable with the sun gear member 442 through the clutch 454. Theplanet carrier assembly member 426 is selectively connectable with thering gear member 434 through the clutch 456. The planet carrier assemblymember 426 is selectively connectable with the planet carrier assemblymember 446 through the clutch 457. The sun gear member 442 isselectively connectable with the transmission housing 460 through thebrake 458. The planet carrier assembly member 446 is selectivelyconnectable with the transmission housing 460 through the brake 459.

The truth table shown in FIG. 5 b describes the engagement combinationand sequence of the torque-transmitting mechanisms 450, 452, 454, 456,457, 458 and 459 that are employed to provide the forward and reversedrive ratios.

Also given in the truth table of FIG. 5 b is a set of numerical valuesthat are attainable with the present invention utilizing the ringgear/sun gear tooth ratios shown. The N_(R1)/N_(S1) value is the toothratio of the planetary gear set 420; the N_(R2)/N_(S2) value is thetooth ratio of the planetary gear set 430; and the N_(R3)/N_(S3) valueis the tooth ratio of the planetary gear set 440.

FIG. 5 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is2.25.

A powertrain 510, shown in FIG. 6 a, includes an engine and torqueconverter 12, a planetary gear transmission 514 and the final drivemechanism 16. The planetary transmission 514 includes the input shaft17, a planetary gear arrangement 518 and the output shaft 19. Theplanetary gear arrangement 518 includes three planetary gear sets 520,530 and 540.

The planetary gear set 520 includes a sun gear member 522, a ring gearmember 524, and a planet carrier assembly 526. The planet carrierassembly 526 includes a plurality of pinion gears 527 rotatably mountedon a carrier member 529 and disposed in meshing relationship with boththe sun gear member 522 and the ring gear member 524.

The planetary gear set 530 includes a sun gear member 532, a ring gearmember 534, and a planet carrier assembly member 536. The planet carrierassembly member 536 includes a plurality of pinion gears 537 rotatablymounted on a carrier member 539 and disposed in meshing relationshipwith both the sun gear member 532 and the ring gear member 534.

The planetary gear set 540 includes a sun gear member 542, a ring gearmember 544, and a planet carrier assembly member 546. The planet carrierassembly member 546 includes a plurality of pinion gears 547 rotatablymounted on a carrier member 549 and disposed in meshing relationshipwith both the sun gear member 542 and the ring gear member 544.

The planetary gear arrangement 518 also includes seventorque-transmitting mechanisms 550, 552, 554, 556, 557, 558 and 559. Thetorque-transmitting mechanisms 550, 552, 554, 556 and 557 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 558 and 559 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member522. The output shaft 19 is continuously connected with the ring gearmember 544. The sun gear member 532 is continuously connected with thetransmission housing 560.

The sun gear member 522 is selectively connectable with the planetcarrier assembly member 536 through the clutch 550. The ring gear member524 is selectively connectable with the planet carrier assembly member536 through the clutch 552. The planet carrier assembly member 526 isselectively connectable with the ring gear member 534 through the clutch554. The planet carrier assembly member 526 is selectively connectablewith the planet carrier assembly member 546 through the clutch 556. Thering gear member 534 is selectively connectable with the sun gear member542 through the clutch 557. The planet carrier assembly member 546 isselectively connectable with the transmission housing 560 through thebrake 558. The sun gear member 542 is selectively connectable with thetransmission housing 560 through the brake 559.

The truth table shown in FIG. 6 b describes the engagement sequence andcombination of the torque-transmitting mechanisms to provide the tworeverse speed ratios and eight forward speed ratios. The chart of FIG. 6b describes the ratio steps between adjacent forward speed ratios andthe ratio step between the reverse and first forward speed ratio.

The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6 b. TheN_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 520;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set530; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 540.

A powertrain 610, shown in FIG. 7 a, has the engine and torque converter12, a planetary transmission 614 and the final drive mechanism 16. Theplanetary transmission 614 includes the input shaft 17, a planetary geararrangement 618 and the output shaft 19. The planetary gear arrangement618 includes three planetary gear sets 620, 630 and 640.

The planetary gear set 620 includes a sun gear member 622, a ring gearmember 624, and a planet carrier assembly 626. The planet carrierassembly 626 includes a plurality of pinion gears 627 rotatably mountedon a carrier member 629 and disposed in meshing relationship with boththe sun gear member 622 and the ring. gear member 624.

The planetary gear set 630 includes a sun gear member 632, a ring gearmember 634, and a planet carrier assembly member 636. The planet carrierassembly member 636 includes a plurality of pinion gears 637 rotatablymounted on a carrier member 639 and disposed in meshing relationshipwith both the sun gear member 632 and the ring gear member 634.

The planetary gear set 640 includes a sun gear member 642, a ring gearmember 644, and a planet carrier assembly member 646. The planet carrierassembly member 646 includes a plurality of pinion gears 647 rotatablymounted on a carrier member 649 and disposed in meshing relationshipwith both the sun gear member 642 and the ring gear member 644.

The planetary gear arrangement 618 also includes seventorque-transmitting mechanisms 650, 652, 654, 656, 657, 658 and 659. Thetorque-transmitting mechanisms 650, 652, 654, 656 and 657 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 658 and 659 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member632. The output shaft 19 is continuously connected with the ring gearmember 644. The ring gear member 634 is continuously connected with thetransmission housing 660.

The planet carrier assembly member 626 is selectively connectable withthe sun gear member 642 through the clutch 650. The planet carrierassembly member 626 is selectively connectable with the ring gear member644 through the clutch 652. The ring gear member 624 is selectivelyconnectable with the planet carrier assembly member 646 through theclutch 654. The sun gear member 632 is selectively connectable with theplanet carrier assembly member 646 through the clutch 656. The planetcarrier assembly member 636 is selectively connectable with the sun gearmember 642 through the clutch 657. The planet carrier assembly member626 is selectively connectable with the transmission housing 660 throughthe brake 658. The sun gear member 622 is selectively connectable withthe transmission housing 660 through the brake 659.

The truth table shown in FIG. 7 b describes the combination oftorque-transmitting mechanism engagements that will provide the reversedrive ratio and eight forward speed ratios, as well as the sequence ofthese engagements and interchanges. The torque-transmitting mechanisms654, 657 and 659 can be engaged through the neutral condition, therebysimplifying the forward/reverse interchange.

The ratio values given are by way of example and are establishedutilizing the ring gear/sun gear tooth ratios given in FIG. 7 b. Forexample, the N_(R1)/N_(S1) value is the tooth ratio of the planetarygear set 620; the N_(R2)/N_(S2) value is the tooth ratio of theplanetary gear set 630; and the N_(R3)/N_(S3) value is the tooth ratioof the planetary gear set 640. The ratio steps between adjacent forwardratios and the reverse to first ratio are also given in FIG. 7 b.

A powertrain 710, shown in FIG. 8 a, has the conventional engine andtorque converter 12, a planetary transmission 714, and the conventionalfinal drive mechanism 16. The engine and torque converter 12 aredrivingly connected with the planetary transmission 714 through theinput shaft 17. The planetary transmission 714 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 714 includes a planetary gear arrangement 718that has a first planetary gear set 720, a second planetary gear set730, and a third planetary gear set 740.

The planetary gear set 720 includes a sun gear member 722, a ring gearmember 724, and a planet carrier assembly 726. The planet carrierassembly 726 includes a plurality of pinion gears 727 rotatably mountedon a carrier member 729. The pinion gears 727 are disposed in meshingrelationship with the sun gear member 722 and the ring gear member 724.

The planetary gear set 730 includes a sun gear member 732, a ring gearmember 734, and a planet carrier assembly member 736. The planet carrierassembly member 736 includes a plurality of pinion gears 737 rotatablymounted on a carrier member 739 and disposed in meshing relationshipwith both the sun gear member 732 and the ring gear member 734.

The planetary gear set 740 includes a sun gear member 742, a ring gearmember 744, and a planet carrier assembly member 746. The planet carrierassembly member 746 includes a plurality of pinion gears 747 rotatablymounted on a carrier member 749 and disposed in meshing relationshipwith both the sun gear member 742 and the ring gear member 744.

The planetary gear arrangement 718 also includes seventorque-transmitting mechanisms 750, 752, 754, 756, 757, 758 and 759. Thetorque-transmitting mechanisms 750, 752, 754, 756 and 757 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 758 and 759 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member732. The output shaft 19 is continuously connected with the ring gearmember 724. The ring gear member 734 is continuously connected with thetransmission housing 760.

The planet carrier assembly member 726 is selectively connectable withthe sun gear member 742 through the clutch 750. The planet carrierassembly member 726 is selectively connectable with the planet carrierassembly member 746 through the clutch 752. The sun gear member 722 isselectively connectable with the ring gear member 744 through the clutch754. The sun gear member 732 is selectively connectable with the sungear member 742 through the clutch 756. The planet carrier assemblymember 736 is selectively connectable with the ring gear member 744through the clutch 757. The planet carrier assembly member 726 isselectively connectable with the transmission housing 760 through thebrake 758. The sun gear member 722 is selectively connectable with thetransmission housing 760 through the brake 759.

The truth table of FIG. 8 b defines the torque-transmitting mechanismengagement sequence utilized for each of the forward and reverse speedratios. Also given in the truth table is a set of numerical values thatare attainable with the present invention utilizing the ring gear/sungear tooth ratios given in FIG. 8 b. The N_(R1)/N_(S1) value is thetooth ratio of the planetary gear set 720; the N_(R2)/N_(S2) value isthe tooth ratio of the planetary gear set 730; and the N_(R3)/N_(S3)value is the tooth ratio of the planetary gear set 740.

FIG. 8 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.41.

A powertrain 810, shown in FIG. 9 a, has the conventional engine andtorque converter 12, a planetary transmission 814, and the final drivemechanism 16. The engine and torque converter 12 are drivingly connectedwith the planetary transmission 814 through the input shaft 17. Theplanetary transmission 814 is drivingly connected with the final drivemechanism 16 through the output shaft 19. The planetary transmission 814includes a planetary gear arrangement 818 that has a first planetarygear set 820, a second planetary gear set 830, and a third planetarygear set 840.

The planetary gear set 820 includes a sun gear member 822, a ring gearmember 824, and a planet carrier assembly 826. The planet carrierassembly 826 includes a plurality of pinion gears 827 rotatably mountedon a carrier member 829 and disposed in meshing relationship with thesun gear member 822 and the ring gear member 824.

The planetary gear set 830 includes a sun gear member 832, a ring gearmember 834, and a planet carrier assembly member 836. The planet carrierassembly member 836 includes a plurality of pinion gears 837 rotatablymounted on a carrier member 839 and disposed in meshing relationshipwith both the sun gear member 832 and the ring gear member 834.

The planetary gear set 840 includes a sun gear member 842, a ring gearmember 844, and a planet carrier assembly member 846. The planet carrierassembly member 846 includes a plurality of pinion gears 847 rotatablymounted on a carrier member 849 and disposed in meshing relationshipwith both the ring gear member 844 and the sun gear member 842.

The planetary gear arrangement 818 also includes seventorque-transmitting mechanisms 850, 852, 854, 856, 857, 858 and 859. Thetorque-transmitting mechanisms 850, 852, 854, 856 and 857 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 858 and 859 are stationary-type torquetransmitting mechanisms, commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member832. The output shaft 19 is continuously connected with the ring gearmember 824. The ring gear member 834 is continuously connected with thetransmission housing 860.

The planet carrier assembly member 826 is selectively connectable withthe ring gear member 844 through the clutch 850. The planet carrierassembly member 826 is selectively connectable with the sun gear member842 through the clutch 852. The sun gear member 822 is selectivelyconnectable with the ring gear member 844 through the clutch 854. Thesun gear member 832 is selectively connectable with the sun gear member842 through the clutch 856. The planet carrier assembly member. 836 isselectively connectable with the planet carrier assembly member 846through the clutch 857. The planet carrier assembly member 826 isselectively connectable with the transmission housing 860 through thebrake 858. The sun gear member 822 is selectively connectable with thetransmission housing 860 through the brake 859.

The truth table shown in FIG. 9 b defines the torque-transmittingmechanism engagement sequence that provides the two reverse speed ratiosand eight forward speed ratios shown in the truth table and availablewith the planetary gear arrangement 818. A sample of numerical valuesfor the individual ratios is also given in the truth table of FIG. 9 b.These numerical values have been calculated using the ring gear/sun geartooth ratios also given by way of example in FIG. 9 b. The N_(R1)/N_(S1)value is the tooth ratio of the planetary gear set 820; theN_(R2)/N_(S2) value is the tooth ratio of the planetary gear set 830;and the N_(R3)/N_(S3) value is the tooth ratio of the planetary gear set840. FIG. 9 b also describes the ratio steps between adjacent forwardratios and between the reverse and first forward ratio.

The powertrain 910, shown in FIG. 10 a, includes the conventional engineand torque converter 12, a planetary transmission 914, and theconventional final drive mechanism 16. The engine and torque converter12 are drivingly connected with the planetary transmission 914 throughthe input shaft 17. The planetary transmission 914 is drivinglyconnected with the final drive mechanism 16 through the output shaft 19.The planetary transmission 914 includes a planetary gear arrangement 918that has a first planetary gear set 920, a second planetary gear set930, and a third planetary gear set 940.

The planetary gear set 920 includes a sun gear member 922, a ring gearmember 924, and a planet carrier assembly 926. The planet carrierassembly 926 includes a plurality of pinion gears 927 that are rotatablymounted on a carrier member 929 and disposed in meshing relationshipwith the sun gear member 922 and the ring gear member 924, respectively.

The planetary gear set 930 includes a sun gear member 932, a ring gearmember 934, and a planet carrier assembly member 936. The planet carrierassembly member 936 includes a plurality of pinion gears 937, 938rotatably mounted on a carrier member 939 and disposed in meshingrelationship with the sun gear member 932 and the ring gear member 934,respectively.

The planetary gear set 940 includes a sun gear member 942, a ring gearmember 944, and a planet carrier assembly member 946. The planet carrierassembly member 946 includes a plurality of pinion gears 947 rotatablymounted on a carrier member 949 and disposed in meshing relationshipwith both the sun gear member 942 and the ring gear member 944.

The planetary gear arrangement 918 also includes seventorque-transmitting mechanisms 950, 952, 954, 956, 957, 958. and 959.The torque-transmitting mechanisms 950, 952, 954, 956 and 957 arerotating-type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanisms 958 and 959 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the ring gear member934. The output shaft 19 is continuously connected with the ring gearmember 924. The sun gear member 932 is continuously connected with thetransmission housing 960.

The planet carrier assembly member 926 is selectively connectable withthe ring gear member 934 through the clutch 950. The planet carrierassembly member 926 is selectively connectable with the planet carrierassembly member 946 through the clutch 952. The sun gear member 922 isselectively connectable with the planet carrier assembly member 946through the clutch 954. The sun gear member 922 is selectivelyconnectable with the sun gear member 942 through the clutch 956. Theplanet carrier assembly member 936 is selectively connectable with thesun gear member 942 through the clutch 957. The planet carrier assemblymember 926 is selectively connectable with the transmission housing 960through the brake 958. The ring gear member 944 is selectivelyconnectable with the transmission housing 960 through the brake 959.

The truth table of FIG. 10 b describes the torque-transmitting mechanismengagement sequence utilized to provide the two reverse speed ratios andeight forward speed ratios. The truth table also provides a set ofexamples for the ratios for each of the reverse and forward speedratios. These numerical values have been determined utilizing the ringgear/sun gear tooth ratios given in FIG. 10 b. The N_(R1)/N_(S1) valueis the tooth ratio of the planetary gear set 920; the N_(R1)/N_(S2)value is the tooth ratio of the planetary gear set 930; and theN_(R3)/N_(S3) value is the tooth ratio of the planetary gear set 940.

A powertrain 1010, shown in FIG. 11 a, includes the conventional engineand torque converter 12, a planetary transmission 1014, and theconventional final drive mechanism 16. The engine and torque converterare drivingly connected with the planetary transmission 1014 through theinput shaft 17. The planetary transmission 1014 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 1014 includes a planetary gear arrangement 1018that has a first planetary gear set 1020, a second planetary gear set1030, and a third planetary gear set 1040.

The planetary gear set 1020 includes a sun gear member 1022, a ring gearmember 1024, and a planet carrier assembly 1026. The planet carrierassembly 1026 includes a plurality of pinion gears 1027 rotatablymounted on a carrier member 1029 and disposed in meshing relationshipwith both the sun gear member 1022 and the ring gear member 1024.

The planetary gear set 1030 includes a sun gear member 1032, a ring gearmember 1034, and a planet carrier assembly member 1036. The planetcarrier assembly member 1036 includes a plurality of pinion gears 1037rotatably mounted on a carrier member 1039 and disposed in meshingrelationship with both the sun gear member 1032 and the ring gear member1034.

The planetary gear set 1040 includes a sun gear member 1042, a ring gearmember 1044, and a planet carrier assembly member 1046. The planetcarrier assembly member 1046 includes a plurality of pinion gears 1047rotatably mounted on a carrier member 1049 and disposed in meshingrelationship with both the sun gear member 1042 and the ring gear member1044.

The planetary gear arrangement 1018 also includes seventorque-transmitting mechanisms 1050, 1052, 1054, 1056, 1057, 1058 and1059. The torque-transmitting mechanisms 1050, 1052, 1054, 1056 and 1057are rotating-type torque-transmitting mechanisms, commonly termedclutches. The torque-transmitting mechanisms 1058 and 1059 arestationary-type torque-transmitting mechanisms, commonly termed brakesor reaction clutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 1026. The output shaft 19 is continuously connected withthe ring gear member 1044. The ring gear member 1034 is continuouslyconnected with the transmission housing 1060.

The ring gear member 1024 is selectively connectable with the planetcarrier assembly member 1026 through the clutch 1050. The sun gearmember 1022 is selectively connectable with the sun gear member 1032through the clutch 1052. The ring gear member 1024 is selectivelyconnectable with the planet carrier assembly member 1046 through theclutch 1054. The ring gear member 1024 is selectively connectable withthe planet carrier assembly member 1036 through the clutch 1056. Theplanet carrier assembly member 1036 is selectively connectable with thesun gear member 1042 through the clutch 1057. The planet carrierassembly member 1046 is selectively connectable with the transmissionhousing 1060 through the brake 1058. The sun gear member 1042 isselectively connectable with the transmission housing 1060 through thebrake 1059.

The truth table shown in FIG. 11 b describes the engagement combinationsand the engagement sequence necessary to provide the two reverse driveratios and the eight forward speed ratios. A sample of the numericalvalues for the ratios is also provided in the truth table of FIG. 11 b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 11 b. The N_(R1)/N_(S1) value is the toothratio for the planetary gear set 1020; the N_(R2)/N_(S2) value is thetooth ratio for the planetary gear set 1030; and the N_(R3)/N_(S3) valueis the tooth ratio for the planetary gear set 1040. Also given in FIG.11 b is a chart describing the step ratios between the adjacent forwardspeed ratios and the reverse to first forward speed ratio.

A powertrain 1110, shown in FIG. 12 a, has a conventional engine andtorque converter 12, a planetary transmission 1114, and the conventionalfinal drive mechanism 16. The planetary transmission 1114 includes aplanetary gear arrangement 1118 which is connected with the engine andtorque converter 12 through the input shaft 17 and with the final drivemechanism 16 through the output shaft 19. The planetary gear arrangement1118 includes three planetary gear sets 1120, 1130 and 1140.

The planetary gear set 1120 includes a sun gear member 1122, a ring gearmember 1124, and a planet carrier assembly 1126. The planet carrierassembly 1126 includes a plurality of pinion gears 1127 rotatablymounted on a carrier member 1129 and disposed in meshing relationshipwith both the sun gear member 1122 and the ring gear member 1124.

The planetary gear set 1130 includes a sun gear member 1132, a ring gearmember 1134, and a planet carrier assembly member 1136. The planetcarrier assembly member 1136 includes a plurality of intermeshing piniongears 1137 that are rotatably mounted on a carrier member 1139 anddisposed in meshing relationship with both the sun gear member 1132 andthe ring gear member 1134.

The planetary gear set 1140 includes a sun gear member 1142, a ring gearmember 1144, and a planet carrier assembly member 1146. The planetcarrier assembly member 1146 includes a plurality of pinion gears. 1147rotatably mounted on a carrier member 1149 and disposed in meshingrelationship with both the sun gear member 1142 and the ring gear member1144.

The planetary gear arrangement 1118 also includes seventorque-transmitting mechanisms 1150, 1152, 1154, 1156, 1157, 1158 and1159. The torque-transmitting mechanisms 1150, 1152, 1154, 1156 and 1157are rotating-type torque-transmitting mechanisms, commonly termedclutches. The torque-transmitting mechanisms 1158 and 1159 arestationary-type torque-transmitting mechanisms, commonly termed brakesor reaction clutches.

The input shaft 17 is continuously connected with the ring gear member1124. The output shaft 19 is continuously connected with the planetcarrier assembly member 1146. The planet carrier assembly member 1136 iscontinuously connected with the transmission housing 1160.

The planet carrier assembly member 1126 is selectively connectable withthe ring gear member 1124 through the clutch 1150. The planet carrierassembly member 1126 is selectively connectable with the planet carrierassembly member 1146 through the clutch 1152. The sun gear member 1122is selectively connectable with the sun gear member 1132 through theclutch 1154. The ring gear member 1134 is selectively connectable withthe ring gear member 1144 through the clutch 1156. The ring gear member1134 is selectively connectable with the sun gear member 1142 throughthe clutch 1157. The planet carrier assembly member 1126 is selectivelyconnectable with the transmission housing 1160 through the brake 1158.The ring gear member 1144 is selectively connectable with thetransmission housing 1160 through the brake 1159.

The truth table shown in FIG. 12 b describes the engagement sequence andengagement combinations utilized with the present family member toprovide two reverse drive ratios and eight forward speed ratios, as wellas an extra fourth speed ratio: 4′. The truth table of FIG. 12 b alsoprovides a set of example numbers that can be established in theplanetary gear arrangement 1118 utilizing the ring gear/sun gear toothratios. The N_(R1)/N_(S1) value is the ring gear/sun gear tooth ratio ofthe planetary gear set 1120; the N_(R2)/N_(S2) value is the ringgear/sun gear tooth ratio of the planetary gear set 1130; and theN_(R3)/N_(S3) value is the ring gear/sun gear tooth ratio of theplanetary gear set 1140.

The chart of FIG. 12 b describes the ratio steps between adjacentforward speed ratios for an eight-speed transmission. These step ratiosare established utilizing the example speed ratios given in the truthtable. As also shown in the truth table, the torque-transmittingmechanisms 1150 and 1154 can remain engaged through the neutralcondition, thereby simplifying the forward/reverse interchange.

A powertrain 1210, shown in FIG. 13 a, includes the conventional engineand torque converter 12, a planetary transmission 1214, and theconventional. final drive mechanism 16. The engine and torque converterare drivingly connected with the planetary transmission 1214 through theinput shaft 17. The planetary, transmission 1214 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 1214 includes a planetary gear arrangement 1218that has a first planetary gear set 1220, a second planetary gear set1230, and a third planetary gear set 1240.

The planetary gear set 1220 includes a sun gear member 1222, a ring gearmember 1224, and a planet carrier assembly 1226. The planet carrierassembly 1226 includes a plurality of pinion gears 1227 rotatablymounted on a carrier member 1229 and disposed in meshing relationshipwith both the sun gear member 1222 and the ring gear member 1224.

The planetary gear set 1230 includes a sun gear member 1232, a ring gearmember 1234, and a planet carrier assembly member 1236. The planetcarrier assembly member 1236 includes a plurality of pinion gears 1237rotatably mounted on a carrier member 1239 and disposed in meshingrelationship with both the sun gear member 1232 and the ring gear member1234.

The planetary gear set 1240 includes a sun gear member 1242, a ring gearmember 1244, and a planet carrier assembly member 1246. The planetcarrier assembly member 1246 includes a plurality of pinion gears 1247rotatably mounted on a carrier member 1249 and disposed in meshingrelationship with both the sun gear member 1242 and the ring gear member1244.

The planetary gear arrangement 1218 also includes seven torquetransmitting mechanisms 1250, 1252, 1254, 1256, 1257, 1258 and 1259. Thetorque-transmitting mechanisms 1250, 1252, 1254, 1256, 1257 and 1258 arerotating-type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 1259 is a stationary-typetorque-transmitting mechanism, commonly termed brake or reaction clutch.

The input shaft 17 is continuously connected with the sun gear member1222. The output shaft 19 is continuously connected with the ring gearmember 1244. The sun gear member 1232 is continuously connected with thetransmission housing 1260.

The ring gear member 1224 is selectively connectable with the planetcarrier assembly member 1236 through the clutch 1250. The planet carrierassembly member 1226 is selectively connectable with the sun gear member1242 through the clutch 1252. The planet carrier assembly member 1226 isselectively connectable with the planet carrier assembly member 1246through the clutch 1254. The ring gear member 1234 is selectivelyconnectable with the sun gear member 1242 through the clutch 1256. Thering gear member 1234 is selectively connectable with the planet carrierassembly member 1246 through the clutch 1257. The sun gear member 1222is selectively connectable with the ring gear member 1224 through theclutch 1258. The ring gear member 1234 is selectively connectable withthe transmission housing 1260 through the brake 1259.

The truth table shown in FIG. 13 b describes the engagement combinationsand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios. A sample of the numerical valuesfor the ratios is also provided in the truth table of FIG. 13 b. Thesevalues are determined utilizing the ring gear/sun gear tooth ratios alsogiven in FIG. 13 b. The N_(R1)/N_(S1) value is the tooth ratio for theplanetary gear set 1220; the N_(R2)/N_(S2) value is the tooth ratio forthe planetary gear set 1230; and the N_(R3)/N_(S3) value is the toothratio for the planetary gear set 1240. Also given in FIG. 13 b is achart describing the step ratios between the adjacent forward speedratios and the reverse to first forward speed ratio.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second and third planetary gear sets each having first,second and third members; said input shaft being continuouslyinterconnected with a member of said planetary gear sets, and saidoutput shaft being continuously interconnected with another member ofsaid planetary gear sets; wherein a first member of said secondplanetary gear set is continuously connected with a stationary member; afirst torque-transmitting mechanism selectively interconnecting a memberof said first planetary gear set with a member of said third planetarygear set; a second torque-transmitting mechanism selectivelyinterconnecting a member of said second planetary gear set with a memberof said first or third planetary gear set; a third torque-transmittingmechanism selectively interconnecting a member of said third planetarygear set with a member of said first or second planetary gear set; afourth torque-transmitting mechanism selectively interconnecting amember of said first planetary gear set with a member of said second orthird planetary gear set; a fifth torque-transmitting mechanismselectively interconnecting a member of said first or third planetarygear set with another member of said first, second or third planetarygear set; a sixth torque-transmitting mechanism selectivelyinterconnecting a member of said first, second or third planetary gearset with another member of said first, second or third planetary gearset, or with said stationary member; a seventh torque-transmittingmechanism selectively interconnecting a member of said first or thirdplanetary gear set with another member of said first, second or thirdplanetary gear set, or with said stationary member; saidtorque-transmitting mechanisms being engaged in combinations of four toestablish at least eight forward speed ratios and at least one reversespeed ratio between said input shaft and said output shaft.
 2. Thetransmission defined in claim 1, wherein said first, second, third,fourth, fifth and sixth torque-transmitting mechanisms compriseclutches, and said seventh torque-transmitting mechanism comprises abrake.
 3. The transmission defined in claim 1, wherein said first,second, third, fourth, fifth, sixth and seventh torque-transmittingmechanisms comprise clutches.
 4. The transmission defined in claim 1,wherein said first, second, third, fourth and fifth torque-transmittingmechanisms comprise clutches, and said sixth and seventhtorque-transmitting mechanisms comprise brakes.
 5. The transmissiondefined in claim 1, wherein planet carrier assembly members of each ofsaid planetary gear sets are single-pinion carriers.
 6. The transmissiondefined in claim 1, wherein at least one planet carrier assembly memberof said planetary gear sets is a double-pinion carrier.
 7. A multi-speedtransmission comprising: an input shaft; an output shaft; a planetarygear arrangement having first, second and third planetary gear sets,each planetary gear set having first, second and third members; saidinput shaft being continuously interconnected with a member of saidplanetary gear sets, and said output shaft being continuouslyinterconnected with another member of said planetary gear sets; whereina first member of said second planetary gear set is continuouslyconnected with a stationary member; and seven torque-transmittingmechanisms for selectively interconnecting said members of saidplanetary gear sets with said stationary member or with other members ofsaid planetary gear sets, said seven torque-transmitting mechanismsbeing engaged in combinations of four to establish at least eightforward speed ratios and at least one reverse speed ratio between saidinput shaft and said output shaft.
 8. The transmission defined in claim7, wherein a first of said seven torque-transmitting mechanisms isoperable for selectively interconnecting a member of said firstplanetary gear set with a member of said third planetary gear set. 9.The transmission defined in claim 7, wherein a second of said seventorque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said second planetary gear set with a memberof said first or third planetary gear set.
 10. The transmission definedin claim 7, wherein a third of said seven torque-transmitting mechanismsis selectively operable for interconnecting a member of said thirdplanetary gear set with a member of said first or second planetary gearset.
 11. The transmission defined in claim 7, wherein a fourth of saidseven torque-transmitting mechanisms is selectively operable forinterconnecting a member of said first planetary gear set with a memberof said second or third planetary gear set.
 12. The transmission definedin claim 7, wherein a fifth of said seven torque-transmitting mechanismsis selectively operable for interconnecting a member of said first orthird planetary gear set with another member of said first, second orthird planetary gear set.
 13. The transmission defined in claim 7,wherein a sixth of said seven torque-transmitting mechanisms selectivelyinterconnects a member of said first, second or third planetary gear setwith another member of said first, second or third planetary gear set,or with said stationary member.
 14. The transmission defined in claim 7,wherein a seventh of said seven torque-transmitting mechanismsselectively interconnects a member of said first or third planetary gearset with another member of said first, second or third planetary gearset, or with said stationary member.
 15. The transmission defined inclaim 7, wherein planet carrier assembly members of each of saidplanetary gear sets are single-pinion carriers.
 16. The transmissiondefined in claim 7, wherein at least one planet carrier assembly memberof said planetary gear sets is a double-pinion carrier.